Method and apparatus for monitoring integrated circuit fabrication

ABSTRACT

In one aspect, the present invention is a sensor unit for sensing process parameters of a process to manufacture an integrated circuit using integrated circuit processing equipment. In one embodiment, the sensor unit includes a substrate having a wafer-shaped profile and a first sensor, disposed on or in the substrate, to sample a first process parameter. The sensor unit of this embodiment also includes a second sensor, disposed on or in the substrate, to sample a second process parameter wherein the second process parameter is different from the first process parameter. In one embodiment, the sensor unit includes a first source, disposed on or in the substrate, wherein first source generates an interrogation signal and wherein the first sensor uses the interrogation signal from the first source to sample the first process parameter. The sensor unit may also include a second source, disposed on or in the substrate, wherein second source generates an interrogation signal and wherein the second sensor uses the interrogation signal from the second source to sample the second process parameter. The first sensor and the first source may operate in an end-point mode or in a real-time mode. In this regard, the first sensor samples the first parameter periodically or continuously while the sensor unit is disposed in the integrated circuit processing equipment and undergoing processing. In one embodiment, the first sensor is a temperature sensor and the second sensor is a pressure sensor, a chemical sensor, a surface tension sensor or a surface stress sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to: U.S. Provisional ApplicationSerial No. 60/423,488, entitled “Method and Apparatus for MonitoringIntegrated Circuit Fabrication using Equipment in Wafer (EIW)”, filedNov. 4, 2002. The contents of this provisional application areincorporated by reference herein in its entirety.

BACKGROUND

[0002] Integrated circuit fabrication generally consists of a series ofprocess steps or stages, for example, photolithography, etch, strip,diffusion, ion implantation, deposition, and chemical mechanicalplanarization (also known as chemical mechanical polishing, or “CMP”).At each step or stage, inspections and measurements are conducted tomonitor the equipment which performs the process as well as the overallprocess, individual processes, and interaction and integration amongindividual processes.

[0003] Typically supporting the integrated circuit fabrication processis a complex infrastructure of, for example, materials supply, wastetreatment, support, logistics and automation. Integrated circuitfabrication processes tend to utilize one of the cleanest environmentsin the world.

[0004] Integrated circuits are typically made on or in a semiconductorsubstrate that is commonly known as a wafer. A wafer is a substantiallyround, thin disk, having diameters such as four inches to twelve inches,and thicknesses in the range of two to three quarters of a millimeter.During the fabrication process, materials or layers are added, treatedand/or patterned on or in the wafer to form the integrated circuits.

[0005] With reference to FIG. 1, the equipment employed to fabricateintegrated circuits may be classified, in a functional manner, into twocategories:

[0006] Processing equipment (“PE”): this type of equipment createsphysical or chemical changes to a wafer; for example, equipment used inperforming photolithography, etch, strip, diffusion, ion implantation,deposition and/or chemical mechanical polishing (“CMP”).

[0007] Monitoring equipment (“ME”): this type of equipment measuresand/or analyzes certain parameters on a processed product or test waferin order to, among other things, ensure the process(es) has behavedaccording to specification. That is, MEs measure, evaluate and/oranalyze the integrity of the process(es). For example, MEs includeequipment used in conducting defect inspection, surface profiling,optical or other types of microscopy. Notably, certain MEs may cause orrequire changes to measurement sample wafers. For example, an SEM mayrequire a measurement sample wafer be cross-sectioned in order toanalyze its profile. Indeed, these samples may be special test wafers,instead of product wafers.

[0008] Generally, conventional monitoring equipment consists of thefollowing subsystems or components:

[0009] 1. Source units—i.e., units that generate and direct thetechnique and mechanism of interrogation (for example, electromagneticwave, charged particles, electrical voltages and currents, etc.) towardsthe measurement sample wafer. The technique of interrogation depends onthe parameter being measured. For example, when measuring the smallestfeature sizes made on an integrated circuit, known as Critical Dimension(“CD”), an electron beam may be used to resolve features as small asthose used in integrated circuit manufacturing.

[0010] 2. Sensing units—i.e., devices or circuitry that samples, senses,detects and/or measures the response of the measurement sample to theinterrogation from/by the source unit. The sensing units may include,for example, temperature, light sensors, image sensors, charged particlesensors, voltage and current meters, and/or detectors. In the example ofmeasuring CD using SEM, the electron beam reflected or scattered fromthe wafer is collected to form a high-resolution image of the featuresor profile on the wafer surface.

[0011] 3. Analysis and user interface units—i.e., units that rely on ageneral purpose or specialized computer, algorithms and software toanalyze information collected by the sensing units and present theresults in a suitable format to, for example, process engineers orhigher-level yield management and analysis software.

[0012] 4. Wafer handling units—i.e., units that are responsible forhandling the measurement samples, most likely in the wafer format,including, for example, loading, unloading, aligning, and conditioningwafers.

[0013] Given the number of different parameters that are measured orinspected in assessing the integrity of a process, there are manydifferent types of MEs employed in a typical semiconductor manufacturingfacility. The MEs may utilize different physical principles to detect,inspect or measure one or more parameters that may be used tocharacterize the process. For example, thin-film thickness measurementtools measure the thin films deposited on the wafer utilizing, forexample, ellipsometry, reflectometry, or sheet resistance.

SUMMARY OF THE INVENTION

[0014] There are many inventions described and illustrated herein. Inone aspect, the present invention embeds some or all of thefunctionalities and capabilities of one, some or all of MEs in a waferor wafer-like object. In the present invention, the wafer or wafer-likeobject has the capability to sense, sample, analyze, memorize and/orcommunicate its status and/or experience.

[0015] These active capabilities may be implemented in various differentways. In one embodiment, the “active” wafer or wafer-like objectaccording to the present invention may be disposed in a PE insubstantially the same manner that a product wafer is sent into the samePE. The PE may process the “active” wafer or wafer-like object in thesame or substantially the same manner as it would process a typicalproduct wafer. Moreover, the “active” wafer or wafer-like object mayexit the PE in the same or in substantially the same manner as a productwafer. The “active” wafer or wafer-like object is referred to herein asan Equipment-In-Wafer (“EIW”).

[0016] In certain embodiments of the present invention, after the EIWexits the PE, it may be powered on or enabled to sense, sample,determine and/or provide certain parameters associated with thechange(s) or modification(s) made to the EIW as a result of the previousprocess(es) (for example a deposition process). In addition, the EIW mayanalyze the effects of that processing, memorize and/or communicateinformation representative thereof to a processing unit (for example, ageneral purpose computer). For example, if an EIW is disposed in a PEimplementing a chemical vapor deposition (“CVD”) process and“experiences” that process, after the EIW is removed from the PE, theEIW may sense, sample, analyze, memorize and/or communicate thethickness of the layer deposited by the CVD process at one, some ormulti-locations on the surface of the EIW. This information may be usedto determine whether the CVD PE is performing properly, in specificationor out of specification, and how and where it was in or out ofspecification. In this way, the EIW is providing, among other things,the functionality and capability of an ME that is designed to measurethe thickness of the same CVD deposition layer.

[0017] In certain embodiments, the EIWs may perform its function whileundergoing a given process within the PE. In this regard, the EIW maysense, sample, measure, detect, analyze, memorize and/or communicate its“experience” (i.e., the sampled, measured, detected and/or analyzedinformation) during the process step or stage, which may be the same orsubstantially the same as that experienced by a product wafer. Forexample, where the EIW is disposed in a PE performing a CVD process, theEIW may sense, sample, measure and/or detect the thickness of thedeposited layer at one, some or all of locations on the substrate of theEIW. The EIW may sense, sample, measure and/or detect that thickness atone instance, at a plurality of predetermined or various points in time,or continuously throughout the process.

[0018] The EIW may also memorize the information and/or communicate thatinformation externally (via, for example, wireless transmissiontechniques) for detailed analysis by, for example, a computer and/or thePE. This information may be employed to determine whether, for example,the CVD PE is working in specification or out of specification.

[0019] In one aspect, the present invention is a device, system andtechnique to shrink or reduce one, some or all ME into an EIW havingsuitable circuitry, structures, materials, capabilities and/orintelligence to perform one or some or all of those functions currentlyperformed by conventional ME. In this way, capital equipment of at leastpart of the industry's infrastructure is reduced, minimized, and/oreffectively or practically eliminated.

[0020] The EIW of the present invention may provide one, some or all ofthe following advantages:

[0021] In-situ, holistic system-level monitoring. In this regard, theEIWs may sense and/or memorize and/or communicate while the process istaking place, the process information collected is in-situ.

[0022] Time-sequence recording. The process information may be collectedat different time points during the process, thus it is possible torecord the time-sequence of events.

[0023] Real-time or near real-time feedback. In certain embodiments,EIWs may collect information as the process is taking place and theinformation may be analyzed, in real-time, and provided to the PE, inreal-time, for adjustment of process conditions to enhance and/oroptimize the process results.

[0024] Seamless integration with many existing PE infrastructure. Sincemany PEs are designed to handle and process product wafers or otherproduct substrates, and EIWs are made to have the same or substantiallythe same form factor, weight, and other mechanical and physicalcharacteristics as a product wafer or product substrate, theintroduction of EIWs in the manufacturing flow will often cause minimalchanges, if any, to the existing manufacturing infrastructure.

[0025] Again, there are many inventions described and illustratedherein. This Summary is not exhaustive of the scope of the presentinvention. Moreover, this Summary is not intended to be limiting of theinvention and should not be interpreted in that manner. While certainembodiments, features, attributes and advantages of the inventions havebeen described here, it should be understood that many others, as wellas different and/or similar embodiments, features, attributes and/oradvantages of the present inventions, which are apparent from thedescription, illustrations and claims—all of which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the course of the description to follow, reference will bemade to the attached drawings. These drawings show different aspects ofthe present invention(s) and, where appropriate, like structures,components, materials and/or elements in different figures will belabeled similarly. It is understood that various combinations of thestructures, materials, components, circuitry, fluids, techniques and/orelements other than those specifically illustrated are contemplated andwithin the scope of the present invention.

[0027]FIG. 1 is a high-level view of a typical integrated circuitmanufacturing process;

[0028]FIG. 2 is a schematic representation of a surface profilemeasurement EIW according to one embodiment of the present invention(s);

[0029]FIGS. 3A and 3B are cross-sectional views of a profiling module ofthe surface profile measurement EIW according to one embodiment of thepresent invention;

[0030] FIGS. 4A-D are schematic representations of an EIW according toseveral embodiments of the present invention;

[0031] FIGS. 5A-E are schematic representations of an EIW, according tocertain embodiments of the present invention, that measure a pluralityof parameters;

[0032]FIG. 6 is an exemplary van Der Pauw sheet resistance measurementstructure;

[0033]FIGS. 7A and 7B are schematic representations of an EIW formonitoring conductive film thickness, using a four-probe sheetresistance measurement technique, according to various embodiments ofthe present invention;

[0034]FIG. 8 is a cross-sectional view of a sheet resistance EIWaccording to one embodiment of the present invention;

[0035]FIG. 9 is a cross-sectional view of a sheet resistance EIW havinga built-in or integrated conductive pad according to one embodiment ofthe present invention;

[0036]FIGS. 10A and 10B are a block diagram representation of an EIW formonitoring conductive film thickness, using a modified four-probe sheetresistance measurement technique, according to one embodiment of thepresent invention;

[0037]FIG. 11 is an exemplary four-probe linewidth measurement structureaccording to one embodiment of the present invention;

[0038]FIG. 12 is a block diagram representation of an EIW, including anarray of sheet resistance measurement sensors, according to oneembodiment of the present invention;

[0039]FIGS. 13A and 13B are block diagram representations of an EIW,including an array of temperature sensors, according to severalembodiments of the present invention;

[0040]FIG. 14 is a schematic representation of a thermal coupleaccording to one embodiment of the present invention

[0041] FIGS. 15A-C are block diagram representations of an EIW,including an array of thermal flow-rate sensors, according to severalembodiments of the present invention;

[0042]FIG. 16 is a block diagram representation of an EIW, including aplurality of pyroelectric sensors, according to several embodiments ofthe present invention;

[0043]FIG. 17 is a block diagram representation of an EIW, including aplurality of photoconductive and photovoltaic sensors, according toseveral embodiments of the present invention;

[0044]FIG. 18 is a block diagram representation of an EIW, including aplurality of pressure sensors, according to several embodiments of thepresent invention;

[0045]FIG. 19 is a block diagram representation of an EIW, including aplurality of capacitance sensors, according to several embodiments ofthe present invention;

[0046]FIG. 20 is a block diagram representation of an EIW, including aplurality of ion sensitive FETs (“ISFETs”), according to severalembodiments of the present invention;

[0047]FIG. 21 is a cross-section view of an exemplary MOSFET;

[0048]FIG. 22 is a schematic representation of an ISFET according to oneembodiment of the present invention;

[0049]FIG. 23 is a block diagram representation of an EIW, including aplurality of resonant sensors, according to several embodiments of thepresent invention;

[0050]FIGS. 24A and 24B are cross-sectional views of resonance sensorsaccording to certain embodiments of the present invention; and

[0051]FIG. 25 is a block diagram representation of an EIW, including aplurality of SAW sensors, according to several embodiments of thepresent invention.

DETAILED DESCRIPTION

[0052] In one aspect, the present invention(s) is an Equipment-In-Wafer(“EIW”) having predetermined sources and/or sensors disposed and/orintegrated on or in a wafer, a wafer-like substrate or a platform tosample, sense, detect, characterize, analyze and/or inspect certainparameters during a particular process(es) in the same or substantiallythe same environment as a product wafer (i.e., a wafer having actualintegrated circuits fabricated thereon) would otherwise experience inprocessing or fabrication equipment, for example, integrated circuitprocessing or fabrication equipment.

[0053] In one embodiment, the EIW is a wafer or wafer-like object. Whenthe EIW is a wafer-like object, the EIW may have a different physicalform factor than a product wafer. The processing equipment, however, mayhandle such an EIW without adverse modification to its hardware and/orsoftware. For example, where an EIW includes circuitry, sensors and/orsources to monitor a CVD process, the EIW may have the same orsubstantially the same planar size and shape as a product wafer, but maybe (slightly) thicker. As such, the EIW “behaves” like a thick wafer andthe deposition equipment may handle the EIW with little or nomodification to the equipment.

[0054] In certain embodiments of the present invention, the EIW mayinclude sources integrated on or in the wafer-like platform, but notintegrated sensors. This type of EIW is known as a “Source-EIW”. In thisway, the complexity of the ME may be significantly reduced because theME may only need sensors to recover the salient information. Inaddition, a Source-EIW includes sources that generate an interrogationsignal(s) that is received, measured, sampled, sensed and/or recorded bya sensor (which may be internal or external). A Source-EIW may provideinformation that is not traditionally available because it includessources located, for example, below the surface structure or the surfaceexposed to the process in order to monitor the process.

[0055] For example, in one embodiment, a Source-EIW may include an arrayof light-emitting elements (for example, VCSEL or LED) integrated intoor onto the wafer-like platform. These sources may be employed to directlight into the wafer surface structure from “below” (or within thewafer-like platform). An associated ME may be used, in conjunction withthis Source-EIW to sense, detect, sample and/or measure the light (afterany scattering and/or interference) and analyze the surface layer(s) orstructure(s), for example, spun-on photo resist.

[0056] In another embodiment of the present invention, the EIW mayinclude sensors integrated on or in the wafer substrate, but notintegrated sources. This type of EIW is known as a “Sensor-EIW”. Likethe Source-EIW, the Sensor-EIW may not only reduce the cost andcomplexity of the ME, but may also provide information that istraditionally unavailable.

[0057] For example, a Sensor-EIW may include image sensors integrated onor in the wafer-like platform. The Sensor-EIW may be placed into alithography equipment (for example, an optical stepper or scanner) todirectly sense, sample and/or measure the light intensity and imagepatterns of the aerial image that is otherwise projected on the surfaceof a product wafer. Notably, such a Sensor-EIW may be any image sensoror system described and/or illustrated in application Ser. No.10/390,806, entitled “System and Method for Lithography and MaskInspection” (hereinafter “the '806 Application”), which is incorporatedby reference herein in its entirety. Moreover, such a Sensor-EIW mayperform, or be used or employed in, any method, technique and/orapplication described and/or illustrated in the '806 Application.

[0058] The Sensor-EIW may also include circuitry and components thatprotrude from the surface, hence creating a portion that includes anon-flat surface topography. The circuitry and components are disposedon a wafer-like object that may be handled (automatically or manually)within the equipment. Thus, such an EIW includes a substrate that has asimilar form factor and/or profile as a product wafer, may be handled insimilar ways as a product wafer, and may be employed or disposed in theappropriate wafer processing equipment with minimal or no change to theconfiguration of the equipment.

[0059] Another example of a Sensor-EIW is an EIW having a plurality ofsensors integrated into or onto the wafer substrate to measure, detect,and/or sample the concentration of a given chemical (for example, anetchant) used during a processing step(s). In addition to theconcentration of the chemical, the sensors may also measure, detect,and/or sample the distribution of chemical concentrations on, across, orat selected or various locations on the surface of the wafer duringprocessing.

[0060] An EIW according to another embodiment of the present inventionmay include source(s) and sensor(s), i.e., the combination of thesubsystems, components, capabilities, and functionalities of aSensor-EIW and a Source-EIW. In this way, the EIW is a more completeinspection, data collection and analysis mechanism.

[0061] With reference to FIGS. 2, 3A and 3B, in one embodiment, EIW 10according to one embodiment, includes one or more surface profilemeasurement modules 12 to collect, sample, detect and/or measure theprofile of the surface of EIW 10, or a portion or portions thereof. Thesurface profile measurement modules 12 may be disposed on or insubstrate 14. In addition, control and interface circuitry 16 may alsobe disposed on or in substrate 14. In this way, circuitry 16 mayfacilitate, monitor, initiate and/or control the sampling, detectingand/or measuring of the surface profile of EIW 10, or a selected orpredetermined portion or portions thereof.

[0062] In one embodiment, surface profile measurement modules 12 employlight of different wavelengths or electromagnetic waves as a techniqueof interrogation. For example, EIW 10 may use light sources 18 a-c (forexample, vertical cavity surface emitting laser (“VCSEL”) or lightemitting diodes (“LED”)) that may be integrated or packaged on or intosubstrate 14 of EIW 10. The EIW 10 of this embodiment may also includelight sensors 20 a-o (for example, CMOS image sensors, CCD image sensorsor photodiodes).

[0063] The EIW 10 may also include a predetermined surface layer orstructure 22 (for example, a medium that facilitates light propagationand/or scattering) to accept and/or receive an additional surface layeror structure 24 that is, for example, deposited by the PE duringfabrication/processing. The additional surface layer (or structure) 24deposited during fabrication may be monitored, analyzed, sampled and/ordetected periodically, intermittently or continuously during and/orafter deposition in order to characterize, analyze, detect, inspect,sample and/or sense the deposition process(es) and/or the PE underinvestigation.

[0064] With reference to FIGS. 3A and 3B, surface layer or structure 22may be a layer of dielectric material (for example, SiO₂ or Si₃N₄ in theorder of tens of microns thick) deposited or coated on or above lightsources 18 a-c and light sensors 20 a-o. In operation, the surface layeror structure 22 provides a volume for light 26 from sources 18 a-c totravel toward the surface, be reflected/scattered downward by surfacelayer or structure 24, and then be detected by sensors 20 a-o. Thepositions of sources 18 a-c relative to sensors 20 a-o may be designedso that information of surface layer of structure 24 is sampled, sensed,detected, extracted, determined or analyzed from the intensity of light26 measured, sampled, sensed and/or detected by sensors 20 a-o.

[0065] The arrangement, placement, materials and types of sources 18and/or sensors 20 may be suitably selected to enhance the operation ofEIW 10 in a given or particular environment. Indeed, surface layer orstructure 22 (for example, the dielectric medium) may also be suitablyselected to accommodate a given situation or environment in which theEIW is to be implemented. For example, predetermined surface layer orstructure 22 may be patterned to guide and/or shape the propagation oflight 26 before light 26 is incident on surface layer or structure 24and thereafter measured.

[0066] Further, a grating structure may be integrated into or ontosurface layer or structure 22 so that the medium not only provides avolume for light travel, but also provides light diffraction. In thisway, the light reflected from surface layer or structure 24 may beanalyzed and/or measured using the additional information provided bythe diffraction.

[0067] Moreover, in certain embodiments, EIW 10 may employ acousticoptical modulation (“AOM”) techniques, wherein the refractive indexgrating may be dynamically changed. For example, where an AOM module isintegrated into or onto EIW 10, control and interface circuitry 16 maybe used to control the AOM module and, in response, drive a plurality ofdifferent acoustic waves to induce a plurality of different gratingstructures (for example, the period and amplitude of the grating). Inthis way, sensor(s) 20 may sense, sample, measure, collect and/or detectthe response of the surface layer structure 24.

[0068] Furthermore, the predetermined surface layer or structure 22 (forexample, a dielectric medium) may be comprised of multiple layers of thesame or different materials. The composite dielectric structure may bepatterned to provide further information regarding the surface layer orstructure 24 that is deposited, formed, or modified on EIW 10 during thefabrication process under investigation.

[0069] In one embodiment, the intensity of the light output by source 18may be varied, modified, changed and/or modulated (including therelative strength between the light source elements) to providedifferent illumination conditions to surface layer or structure 24.Moreover, in another embodiment, the relative intensities of the lightoutput by the plurality of sources 18 a-c may be varied, modified,changed and/or modulated to provide still different illuminationconditions to surface layer or structure 24. The information collected,measured, detected and/or sampled by sensor(s) 20, under theillumination conditions, may be analyzed (for example, via an externalor off-wafer computer using suitable analysis software or algorithms) tocharacterize the surface of layer or structure 24, for example,characterize the thickness and profile of the layer or structure 24deposited, added, or modified during process under investigation.

[0070] With continued reference to FIGS. 2, 3A and 3B, in certainembodiments, EIW 10 may include a plurality of sources 18 and/or aplurality of sensors 20, for example, an array of sources and/or anarray of sensors. The plurality of sources and sensors illustrated inFIGS. 3A and 3B may be replicated in the x- and y-directions to form 2Darray(s). In this way, the EIW may collect, sample and/or measure aspatial distribution of the surface layer or structure 24.

[0071] It should be noted that the EIW structure referenced in FIGS. 2,3A and 3B, can be easily modified to have either source-only orsensor-only, and hence creates corresponding “Source-EIW” and“Sensor-EIW”, as described above. All other descriptions of the EIW(e.g., regarding layer 22) still apply. The advantages described aboveassociated with “Source-EIW” and “Sensor-EIW” also apply.

[0072] EIWs Employing End-Point and/or Real-Time Modes

[0073] In several embodiments of the present invention, the EIW employscircuitry and techniques to implement an end-point mode and/or areal-time mode.

[0074] In an end-point mode, the EIW of the present inventionexperiences the same or substantially the same conditions, or undergoesthe same processing, as a product wafer experiences during a PE process.After the process is completed, the end-result of the physical and/orchemical changes on the EIW is measured, detected, sensed, sampled,determined and/or analyzed. For example, after completion of a CVDdeposition process, the sources and/or sensors may measure the thicknessof a deposited layer of a dielectric layer (for example, silicon dioxide(SiO2)) or a conductive layer (for example, heavily doped silicon oraluminum). Thus, in the end-point mode, the sources and/or sensorsmeasure, detect, sense, sample, determine and/or analyze the end-resultsof the process without measuring, detecting, sensing, sampling theparameter(s) (for example, temperature, pressure, light intensity,chemical composition, concentration and/or density, surface tension,stress, composition and/or profile, voltage, and/or current) or changestherein, during the process.

[0075] With reference to FIGS. 4A-D, in a real-time mode, EIW 10 may beused to monitor, measure, detect, sense, sample, determine, analyzeand/or record a parameter(s) under investigation during the performanceof the process (i.e., time-sequence of the measured parameter(s)), forexample, a change of thickness of a deposited layer as a function oftime. As such, real-time EIW 10 includes a real-time sensor unit 28which is operational and/or functional while real-time EIW 10 is being“processed” by the PE. In this regard, EIW 10 may enable real-timesensor unit 28 (i.e., the source(s) and/or sensor(s)) to measure,detect, sense, sample and/or record the processing “experience” in realtime. At the conclusion of the process step (or during the processstep), EIW 10 provides data that reflects or is representative of theprocessing experience or sequence. The data (which may be of the actualparameter or a representation thereof) may be output to a computer,processor and/or controller 30 (via, for example, wired, wireless and/oroptical techniques) and analyzed, for example, to reconstruct thetime-sequence of the processing experience.

[0076] For example, an EIW having surface resist profile measurementsensor(s) and/or sources (and associated circuitry), may output (inreal-time or the conclusion of the process) data that may be used toillustrate, describe and/or characterize a time sequence of thedeposition and development of the resist profile. In certainembodiments, the time sequence may represent the entire processing timeor portion thereof. Such information may provide process developmentengineers insight into the process, and hence may facilitate a better ormore accurate or specific characterization and tuning of the process orPE.

[0077] With continued reference to FIGS. 4A and 4B, in one embodiment,EIW 10 includes components or circuitry that are powered, enabled oroperational during the processes. In this regard, EIW 10 may receivepower externally or may include a built-in or integrated power sourceresident on substrate 14 of EIW 10, for example, batteries 32, toturn-on, engage or enable resident and/or integrated sources and/orsensors. The batteries 32 may be rechargeable with a thin form factor tobe embedded into EIW 10. To minimize the disruption to the PE, it may beadvantageous to include an electrical power supply (for example,batteries 32) on or in EIW 10 so that EIW 10 is a more self-containedand/or self-sufficient device.

[0078] In other embodiments, electrical power may be provided either viawired or wireless techniques to EIW 10. For example, electrical powermay be obtained from the PE.

[0079] In another embodiment, the real-time EIW includes data storage 34and/or communications circuitry 36. Given that real-time EIWs are usedto sense, sample, measure and/or collect discrete data or data which isrepresentative of the time sequence of certain measurements, the datamay be stored in the data storage 34, for example, a solid state memorysuch as DRAM or Flash, for later retrieval or transmission during datacollection/acquisition. In addition, in certain embodiments, the datamay be downloaded from the EIW in real-time (or nearly real-time) via acommunications circuitry 36 to an external device, such as a computer orcontroller 30 or an external data storage device (not illustrated). Thisreal-time (or near-real-time) communications link may be implementedusing wireless, wired and/or optical techniques.

[0080] Where the EIW employs wired communication techniques, a socket orconnector 38, disposed on the wafer-like substrate or platform, providesa mechanism for external communication (see, FIG. 4B). The socket orconnector may be an electrical connector that includes signal, power andground pins, where signals are transmitted by series of high and lowvoltages, using proprietary or non-proprietary protocols (for example,RS-232). In those embodiments where data storage 34 is employed, thestored data may be retrieved from the EIW via a communications link,which itself may be implemented using wireless, wired and/or opticaltechniques, like that in the description above.

[0081] It should be noted that additional circuitry may be implementedto accommodate bandwidth considerations of the wireless, wired and/oroptical communications techniques. For example, communications betweenthe EIW and an external device (for example, a computer) may be viaoptical, wired and/or wireless of a given bandwidth that may not be ashigh as the bandwidth of the data collection by the sensors. As such,suitable circuitry (for example, data compression circuitry 40 tocompress the data and/or to buffer the data) may be implemented on or inEIW 10 to accommodate the given communications techniques.

[0082] In those embodiments where EIW 10 includes circuitry forreal-time communication of for example, data which is representative ofthe time sequence of the measured parameter, EIW 10 facilitatesreal-time feedback—that is, real-time adjustment, tuning, and/or controlof the process and/or PE. For example, where the EIW is employed tomeasure film thickness during CMP, EIW 10 may provide feedback, in realtime, of film thickness distribution across the surface of substrate 14of EIW 10. These embodiments may allow the PE to adjust the pressure forcertain areas of the wafer, or stop processing when the polishingreaches or achieves a desired specification.

[0083] It should be noted that in certain embodiments, wirelesscommunication methods may minimize disruption to the operation of thePE. This is particularly the case in those situations where the PE doesnot include a means of communication and where the EIW is underprocessing constraints that, as a practical matter, prohibitcompromising the environment of those constraints.

[0084] In those embodiments facilitating real-time data acquisitionand/or analysis, EIW 10 may be employed to enhance or optimize the yieldof the PE as well as the quality, yield and cost of integrated circuitsfabricated using that equipment. The control loop from the PE to sensor,then to computer (which process the data and/or determines corrective orresponsive measures), then back to the equipment, is a type of controlloop that facilitates enhancement or optimization of the process and/orthe PE. In this regard, EIW 10 of this embodiment may allow orfacilitate intermittent, periodic and/or continuous tuning and/oradjustment of the PE and/or the process. That is, the PE and/or theprocess may be tuned or adjusted when EIW 10 enters and exits theequipment as well as undergoes processing by that equipment.

[0085] It should be noted that some or all of the real-time dataanalysis may be performed by circuitry and devices resident on the EIW,for example by controller 16. As such, an external computer orcontroller 30, in this embodiment, maybe avoided. This may be especiallyuseful when the data analysis is not computationally extensive.

[0086] Further, in another embodiment, some or all of the real-time dataanalysis may be conducted or performed by the PE equipment. In thisembodiment, external computer or controller 30 and on-EIW data analysiscapabilities may be unnecessary.

[0087] It should be further noted that the EIW may be enabled and/orequipped with circuitry to facilitate implementation of the real-timemode as well as end-point mode. In this way, both modes of operationand/or analysis are available.

[0088] EIW Having Multiple Sensors and/or Sources to Sample and/orRecord Multiple Parameters

[0089] With reference to FIGS. 5A-E, EIW 10 according to otherembodiments of the present invention may include a plurality ofdifferent types of sensors that measure the same parameter(s) and/ordifferent parameters, for example, sensors to measure, sense, sampleand/or detect physical, chemical, optical and/or electrical parameters.Indeed, the sensors may be disposed in an array on substrate or platform14 of EIW 10 or distributed in a predetermined or random pattern. Forexample, in a complex process such as CMP, it may be advantageous tomonitor multiple parameters at the same time, including chemicalcomposition and/or concentration, pressure applied on the wafer, and/orthickness of the remaining metal film. Moreover, it may be advantageousto provide multiple and/or different light sources (for example, aplurality of LED devices and/or a plurality of VCSEL arrays) to obtainsimilar or the same information.

[0090] It should be noted that the discussions of, for example,electrical power supply techniques and circuitry, as well as thecommunications link, techniques and circuitry, are fully applicable tothis aspect of the present invention. For the sake of brevity, thosediscussions will not be repeated.

[0091] EIW Integration and Packaging

[0092] The EIW of the present invention(s) may be comprised a monolithicstructure (i.e., circuitry, sensors and/or sources integrated within thewafer and manufactured on the same original wafer substrate), orcomprised of discrete components (i.e., sensors, sources, circuitcomponents) packaged and interconnected into or onto the wafer-likeplatform, or a combination thereof (i.e., a hybrid device where some ofthe circuitry, sensors and/or sources integrated within the wafer andsome components integrated on the wafer).

[0093] A monolithic EIW includes electronics (i.e., sensors, sourcesand/or associated control, transmission and/or storage electronics) thatare integrated within the substrate using, for example, VLSI or LSIintegration techniques. Given the current state of technology, the powersource (if any) and/or connector (if any) are more likely incorporatedon the substrate as discrete components. Indeed, in one embodiment, thepower source may be disposed in cavities, holes or cut-outs in thesubstrate in order to minimize the profile of the EIW. (See, forexample, the '806 Application, which, as mentioned above, isincorporated by reference herein in its entirety).

[0094] It should be noted that in discrete and hybrid approaches, whichmay be a preferred approach since it may reduce the complexity and costof EIW 10, the substrate (or portions thereof may be more like a printedcircuit board that is shaped like a typical product wafer. As mentionedabove, in the discrete or hybrid embodiments, certain electronics areindividually and separately made. Those discrete components may bepackaged or un-packaged before integration onto the substrate of theEIW. Indeed, in those circumstances where certain electronics of the EIWis comprised of discrete components, it may be advantageous to employsurface mount devices, unpackaged die and/or cavities, holes or cut-outsin the substrate in order to further minimize the profile of the EIW.Accordingly, in certain embodiments of the discrete-type and hybrid-typeEIW, the EIW may be thicker than an actual product wafer, but may bewithin a thickness range that can be handled (manually or automatically)and processed by the processing equipment with little or no change tothe equipment.

[0095] Thus, in sum, the EIW according to certain embodiments of thepresent invention includes a profile (for example, height and shape, andflatness, if pertinent) that facilitates implementation in PEs much likea product wafer and maintains a form or appearance, during processing,that is substantially similar to that of a product wafer. Moreover, thewafer-shaped platform or substrate may permit automated handling by arobotic loader of the processing equipment. Further, electrical powermay be supplied to the sensor(s) and/or source(s) by a battery(rechargeable or otherwise) and/or the processing equipment; anddata/command transmission may be accomplished using wired, wirelessand/or optical techniques.

[0096] Reusable EIW

[0097] In certain embodiments, the EIW may be reused or reusable. Inthis regard, after use within a given process, the physical changes, ifany, that the PE caused or created on or in the EIW may be “reversed”.In this way, the EIW may be reused to characterize the same or differentprocesses. For example, where an EIW had been employed to measure and/orinspect resist development processes, after data collection andanalysis, the developed resist may be removed (for example, strippedaway). In this regard, the resist would be removed thereby exposing theunderlying surface of the EIW, which would remain intact during andafter the resist removal process. As such, after the resist is removed,the EIW may be employed again, for example, to measure and/or inspectanother spin-coated photo resist process.

[0098] In other embodiments, the EIW may be treated as a “consumable”,and used only once or a few times and then discarded or recycled.

[0099] EIW Substrate, Platform or Workpiece 14

[0100] Many aspects of the invention have been (or will be) described inthe context of integrated circuit manufacturing where the substrate is asemiconductor wafer. In other applications or industries, the substrateor workpiece of concern may take a different form factor and may be madefrom different materials. For example, in manufacturing flat paneldisplays, the substrate or workpiece may be a high quality glass plate.In manufacturing components of hard disk drives, the substrate orworkpiece may be wafer-like, but comprised of materials other than thoseused in manufacturing integrated circuit. In printed circuit board (PCB)manufacturing, the substrate or workpiece may be a circuit board.

[0101] Thus, the present invention(s) may be implemented using a givensubstrate form-factors and/or materials of a particular application inwhich the invention is implemented. Such substrates may include one,some or all of the functionalities and capabilities described herein.Indeed, other functionalities and capabilities may be desired dependingupon the particular application in which the invention is implemented.

[0102] As an example, an EIW according to the present invention may beimplemented to analyze mask fabrication. Briefly, by way of background,in the integrated circuit industry, integrated circuits are fabricatedon wafers (for example, made from silicon or other types ofsemiconductors such as gallium arsenide). An important step in thefabrication process is the manufacturing of masks. In opticallithography, a mask is a high quality glass (for example, quartz) withpatterned chrome coated on one side. After mask fabrication, the chromelayer will contain the master copy of the circuit pattern (or portionthereof) to be duplicated on the product wafers.

[0103] In one embodiment of the present invention, an EIW, having one,some or all of the attributes/features described earlier, may beimplemented in the mask or mask-shaped object to monitor the mask makingprocess. In this regard, a mask or mask-like object is made withsensors, sources, and/or measuring/communication electronics integratedon or in the substrate of the EIW. The EIW of this embodiment may bedescribed as a “Mask-EIW”.

[0104] In one embodiment, the Mask-EIW is fabricated with thermalsensors disposed or integrated on or in a mask to monitor thetemperature, temperature distribution, gradients and/or fluctuationsduring the manufacturing of a mask (for example, during electron-beammask writing and/or during mask resist baking). In another embodiment,EIW may employ chemical sensors to detect, monitor and/or measure anetchant's concentration and/or the etchant's strength during a wetetching process.

[0105] In yet another embodiment, the Mask-EIW may include lightsensor(s), or an array of light sensors, and electronics, communicationand power such that it may be disposed on a chuck or onto the mask stageof a projection lithography system (for example, a stepper or scanner).This embodiment may be used to measure light intensity distribution andother parameters associated with the illumination or optical sub-systemof the lithography equipment. In-situ tuning, enhancement andoptimization may be achieved, as described above.

[0106] The present invention may be implemented using a plurality ofsources and/or sensors and/or techniques to monitor the fabricationprocess or PE. As described below, there are many different types ofsources and/or sensors (alone or in

[0107] combination) that may be incorporated into or onto an EIW.

[0108] EIW Embodiment(s) to Monitor Conductive Film Thickness UsingSheet Resistance Measurement Techniques:

[0109] In one embodiment, the EIW may measure, detect, and/or sample thethickness of a material using sheet resistance. In this regard, sheetresistance (Rs) of a conductive film is defined as the resistance of asquare-shaped area and may be expressed as:

Rs=ρ/d

[0110] where:

[0111] ρ=the resistivity of the conductive material, and

[0112] d=the thickness of the film.

[0113] Thus, for certain materials for which the resistivity is known,the film thickness may be determined using the sheet resistance.

[0114] For measuring sheet resistance, in one embodiment, the presentinvention employs the technique of van der Pauw [see, for example, vander Pauw, “A Method of Measuring Specific Resistivity and Hall Effect ofDiscs of Arbitrary Shapes,” Philips Res. Repts. 13, 1-9 (1958), and, vander Pauw, “A Method of Measuring the Resistivity and Hall Coefficient onLamellae of Arbitrary Shape,” Philips Tech. Rev. 20, 220-224 (1958),incorporated herein by reference]. A common geometry for such ameasurement has four electrical contacts at the four corners of aroughly square sample (see, for example, FIG. 6).

[0115] It is noted that the van der Pauw technique may be applicable foran arbitrary shaped sample provided the thickness of the sample isuniform or substantially or relatively uniform, the contact areas aresmall, and the contacts are all on the perimeter of the sample. In thiscase, van der Pauw demonstrated that:

exp(−πR _(CD,AB) /Rs)+exp(−πR _(BD,AC) /Rs)=1

[0116] where:

[0117] R_(CD,AB)=the resistance determined by dividing the potentialdifference between C and D by the current going from A to B, and

[0118] R_(BD,AC)=the resistance determined by dividing the potentialdifference between B and D by the current going from A to C.

[0119] Using the measured resistance values R_(CD,AB) and R_(BD,AC), thesheet resistance may be determined by solving van der Pauw'sequation/relation. With the known resistivity, the film thickness may bedetermined. It should be noted that the van der Pauw method is alsocommonly referred to as four-probe sheet resistance measurementtechnique.

[0120] With reference to FIGS. 7A and 7B, EIW 10 may incorporate sheetresistance measurement techniques. In particular, with reference to FIG.7B, EIW 10 may include a plurality of van der Pauw like structures,illustrated as Metal pad with four-probe 52. The EIW 10 of thisembodiment may also include a power supply (for example, batteries 32),control and interface circuitry 16 to provide, for example,synchronization, clock generation, memory management, interfacemanagement, interchip communication, and/or calibration and compensation(for example, temperature compensation). The control and interfacecircuitry 16 may also include or consist of microprocessor, memorydevice, FPGA, DSP, and/or ASIC; wherein firmware may be residenttherein.

[0121] The EIW 10 of this embodiment may also include measurementelectronics, for example, voltage and current meters 54 having currentsource, current measurement, voltage measurement, and ADC/DACcircuitry/components. In addition, data storage 34 may reside on or inthe substrate of EIW 10 to store the data measured, sampled, detectedand/or collected during processing. The data storage 34 may benon-volatile memory like flash memory or volatile memory such as DRAM.The EIW 10 may employ wired, optical and/or wireless transmissiontechniques.

[0122] It should be noted that EIW 10 according to this embodiment, aswith the other embodiments, may be tailored according to, for example,its desired use. That is, EIW 10 may contain some or all of thecircuitry discussed above. For example, power and communications may beimplemented in a variety of different manners (as described above). Forthe sake of brevity, those permutations and discussions will not berepeated. Moreover, the EIW of this embodiment may be a Source-EIW or aSensor-EIW.

[0123] With reference to FIG. 8, in one embodiment, EIW 10 of thisembodiment may be fabricated using the four-probe structure 52 that ispartially “buried” in substrate 14 but exposed on the surface of EIW 10.In this regard, electrode C and D are illustrated. Electrode A and B(not illustrated) may be implemented in the same manner. The conductivefilm 56 to be monitored is deposited on (or above) the surface ofsubstrate 14 and is in electrical contact with electrodes A, B, C and D.In this way, the arrangement forms van der Pauw structure or four-probestructure 52.

[0124] During the deposition or polishing of conductive film 56, EIW 10senses, samples, measures and/or detects the sheet resistance atpredetermined, random, or periodic time intervals, and hence recordsand/or communicates the film's thickness and sequence of the film'sthickness versus time. Indeed, the sheet resistance may be sampled,measured and/or detected periodically or continuously for a portion ofor the entire deposition or polishing process. In this way, EIW mayobtain information that provides a more complete characterization ofdeposition or polishing process.

[0125] With reference to FIGS. 9 and 10, in those instances where theforming of deposited material in shapes like a line(s)/space(s) orcontact(s), in lieu of, or in addition to a pad structure illustrated inFIG. 8, it may be advantageous to employ integrated base pad 58 withinor on EIW 10 to facilitate sampling, measuring and/or detecting thesheet resistance of the deposited material. In this regard, integratedbase pad 58 may be “provided” by EIW 10 before deposition of additionalmaterial 60. The additional conductive material 60 is deposited on basepad 58 to form a desired pattern, which is in electrical contact withbase pad 58.

[0126] It should be noted that any desired pattern(s) may be formed onthe integrated base pad 58.

[0127] With continued reference to FIGS. 9 and 10, the relation betweensheet resistance and film thickness may deviate from the van der Pauwequation expressed above. However, with a pattern and known resistivityof both pad 58 and deposited layer 60 a-60 d (FIG. 9), 60 a-e (FIG. 10A)and 60 a-60 t (FIG. 10B), the relation between measured sheet resistanceand the film thickness may be derived and/or numerically solved usingfirst-principle equations (for example, Maxwell Equations).

[0128] It should be noted that there are many techniques of using afour-probe sensor to measure sheet resistance, all of which, whether nowknow or later developed, are intended to be within the scope of thepresent invention. For example, with reference to FIG. 11, four-probetechnique is illustrated where a current is applied/supplied betweenelectrodes A and B, and voltage drop is measured between electrodes Cand D. The relation may be expressed as:

R _(CD,AB) =Rs*(L/W)

[0129] where

[0130] R_(CD,AB)=the resistance determined by dividing the potentialdifference between C and D by the current going from A to B,

[0131] L=the distance between C and D, and

[0132] W=the line width of the conductive line.

[0133] It should be noted that there are many applications of EIW 10that is configured to monitor sheet resistance. For example, theapplications may include (1) monitoring film growth or deposition (forexample, sputtering, CVD, LPCVD, and PECVD) process; and (2) monitoringpolishing and lapping process (for example, CMP).

[0134] EIW Embodiment(s) to Characterize CD Uniformity and DistributionUsing Conductive Film Techniques:

[0135] The embodiments of FIG. 11 may also be employed to sampleelectrical test structure for critical dimension (“CD”) measurements. Asdescribed above, the relationship describing this structure may beexpressed as:

R _(CD,AB) =Rs*(L/W)

[0136] As such, where the sheet resistance “Rs” is known (for example,from a van der Pauw located close to a test structure), and the linelength “L” between C and D is known, the linewidth may be determinedfrom the measurement of R_(CD,AB). This technique is widely used insemiconductor manufacturing in measuring linewidth using electricaltest.

[0137] With reference to FIG. 12, EIW 10 may include the structure todetermine linewidth measurement. The EIW 10 may include an electricaltest structure at multiple locations, for example, an array 62 of metalpad with four-probe structures 52 a-i, across substrate 14, togetherwith associated metal pad with four-probe structure 52 located near toeach linewidth test structure.

[0138] The EIW 10 may include integrated electrodes and/or electronics(current source, current and voltage meters, and control) as describedabove with respect to FIGS. 7A, 7B, 8 and 9. In operation, the PEcreates or deposits additional conductive pad 60 that, together with thebuilt-in electrodes (i.e., electrodes A-D), forms the electricallinewidth test structures. The EIW 10 may also sense, detect, sample anddetermine as well as characterize and/or analyze the linewidthdistribution across the wafer after and/or during the process, asdescribed above in conjunction with the embodiments of FIGS. 7A, 7B, 8and 9.

[0139] Further, the location of the built-in electrodes (electrodes A-D)of EIW 10 may be predetermined and/or selected to measure CD forspecific or selected portions or part(s) of a given product. Forexample, it may be desirable to monitor the linewidth of one, some orall of the lines associated with the transistors of a state of the artmicroprocessor (i.e., the given product). The information of the linesand associated linewidths to be measured may be employed to “layout”sensors 52 a-g or EIW 10. That is, electrodes and the associatedelectronics of sensors 52 a-g may be spatially positioned or located tomeasure the designated, one or more linewidths. In this regard, EIW 10becomes a CD measurement tool that may be advantageously implemented inthe manufacturing of a particular product or integrated circuit device(i.e., microprocessor). One advantage of doing so is that the designatedEIW will provide information that reflects the actual circuits beingdesigned and manufactured, which may not be available from measurementsthat uses only simplified test structures.

Additional EIW Embodiments

[0140] The EIW of the present invention may be implemented using a widevariety of sensor and techniques of sensing and/or sampling, forexample, temperature sensors, pressure sensors, voltage sensors, ionsensors, photo sensors, and/or chemical sensors. Several of thesesensors (and actuators) are based on solid-state technology, which mayfacilitate integration on or in the wafer or wafer-like platform of theEIW of the present invention. Such a configuration allows the EIW tomaintain a profile that is well suited for implementation in currentintegrated circuit fabrication processes.

[0141] Many of these sensors are based on micro electro-mechanicalsystems (MEMS) technology. These sensors are typically manufactured fromor on silicon wafers using processes that are similar to those used inintegrated circuit manufacturing. As such, the EIW of the presentinvention may be implemented using MEMS sensors (and actuators) that areintegrated into or onto a wafer or wafer-shaped substrate to performprocess monitoring, measuring and/or sampling functions.

Thermal Sensors

[0142] As mentioned above, an EIW according to one embodiment of thepresent invention may include thermal sensors. With reference to FIGS.13A and 13B, thermal sensors 64 a-e disposed or integrated on or in thesubstrate of EIW 10 may be employed to detect, sample, measure, and/ormonitor the temperature distribution, gradients and/or fluctuationsduring manufacture of, for example, a mask. The thermal sensors may be,for example, thermocouples and thermoresistors (thermistors).

[0143] Thermocouples

[0144] Briefly, by way of background, when two dissimilar metals (forexample, copper and iron) are brought together in a circuit, and thejunctions are held at different temperatures, then a small voltage isgenerated and an electrical current flows between them.

[0145] With reference to FIG. 14, thermal sensor 64 may include athermocouple having a sensing junction 66, at temperature Ta, and areference junction 68, at temperature Tb. A high resistance voltmeter 70may measure, sense, sample and/or detect the voltage developed by thethermocouple.

[0146] The open circuit voltage (i.e. as measured by an ideal voltmeterwith infinite input impedance) is related to the temperature difference(Ta−Tb), and the difference in the Seebeck coefficients of the twomaterials (Pa−Pb), and may be derived using the following equation:

V=(Pa−Pb)(Ta−Tb)

[0147] where “V” will typically be of the order of millivolts, or tensof millivolts, for metal thermocouples with temperature differences inthe order of 200° C.

[0148] The thermocouples may also be comprised of semiconductormaterials. Semiconductor materials often exhibit a better thermoelectriceffect than metals. In one embodiment of the present invention, EIW 10includes one or more semiconductor thermocouples is/are integrate ordispose on or in substrate 14. The thermocouples may be interconnected,for example, in series, to make a thermopile, which has a larger outputvoltage than an individual thermocouple.

[0149] It is noted, however, that the high thermal conductivity ofsilicon may make it difficult to maintain a large temperature gradient(Ta−Tb). As such, it may be advantageous to thermally isolate thesensing element from the bulk of the silicon wafer. This may be done byfabricating the device on bridges or beams machined and/or fabricatedfrom silicon.

[0150] Thermoresistors

[0151] In one embodiment of the present invention, the thermocouplesinclude thermoresistors. Briefly, by way of background, the electricalresistivity of metals varies with temperature. Above 200° C., theresistivity varies nearly linearly with temperature. In thisapproximately linear region, the variation of resistivity (r) withtemperature (T) may be characterized as:

r=R(1+aT+bT ²)

[0152] where

[0153] “R”=the resistivity of the material at a reference temperature(0° C.), and

[0154] “a” and “b”=constants specific to the metal employed.

[0155] It should be noted that platinum is often employed because itsresistance variation may be linear with temperature (i.e. “b” isparticularly small).

[0156] It may be advantageous to employ a resistance bridge network todetect a change in resistance because metal thermoresistors generallyhave relatively small resistances, and their rate of change ofresistance with temperature (temperature coefficient of resistance(TCR)) is not particularly large.

[0157] In one embodiment, the present invention may employ semiconductorthermoresistors (or thermistors) to sense, sample and/or detecttemperature distribution, gradients and/or fluctuations of a givenprocess (for example, manufacture of a mask). Semiconductorthermoresistors may be formed from metal oxides or silicon. Generally,semiconductor thermoresistors may not be as accurate or stable as metal(for example, platinum) thermoresistors. However, semiconductorthermoresistors tend to be less expensive to manufacture and may be moreeasily integrated into or onto the substrate of an EIW according to thepresent invention.

[0158] The temperature coefficient resistivity of a thermistor tends tobe highly nonlinear and negative, and quite dependent on the power beingdissipated by the device. The resistivity is typically expressedrelative to the resistivity at 25° C. with no power being dissipated bythe device, and may typically range between 500 Ohms and 10M Ohms.

[0159] It should be noted that due to the negative TCR, the resistor maygo into a self-heating loop: current flowing through the resistor heatsthe resistor, the resistivity drops, more current flows, its temperatureincreases. However, the large TCR permits the thermistors to be coupleddirectly to amplifier circuits without connection to a bridgeconfiguration. Appropriate calibration techniques may be employed toaddress any nonlinearity considerations.

[0160] Notably, microengineering techniques may be used in a variety ofways to enhance thermal sensors. As mentioned above, such techniques maybe used to thermally isolate the sensing element from the remainder ofthe device. Also, arrays of sensors may be implemented to providesignals that are larger than the signal from one sensor. In thoseinstances where the sensor is small and thermally isolated, then itsresponse time (the time the sensor takes to heat/cool in response tochanges in the temperature of the environment) may be quite fast. Withsilicon based sensors there are advantages if electronics wereintegrated into or onto the integrated circuit (for example, calibrationdone on-chip, self-testing), wafer or substrate.

[0161] Thermal Flow-Rate Sensors

[0162] An EIW according to one embodiment of the present invention mayinclude thermal flow-rate sensors. With reference to FIGS. 15A, 15B and15C, thermal sensors 64, as described above, and/or thermal flow-ratesensors 72 may be incorporated into or onto substrate 14 of EIW 10 ofthe present invention to detect, sample, measure, and/or monitor themass flow rate (in addition to temperature and temperature distribution)during a given integrated circuit processing step, for example,sputtering, chemical vapor deposition (“CVD”) or plasma-enhanced CVD(PECVD).

[0163] There are a number of ways by which the rate of flow of gassesand liquids may be monitored using thermal sensors 64. All techniquesand configurations to detect, sample, measure, and/or monitor the massflow rate, whether now known or later developed, are intended to fallwithin the scope of the present invention provided such techniques andconfigurations may be implemented into or onto an EIW of the presentinvention. For example, in one embodiment, a first sensor may measurethe temperature of a fluid as it enters the sensor and a second sensormay measure the temperature as it exists the sensor (after the fluid hasbeen passed over a heating resistor). The temperature differencemeasured by the first sensor and the second sensor may be inverselyproportional to the mass flow rate.

[0164] In another embodiment, EIW 10 employs a thermal sensor that ismaintained at a constant temperature (using heating resistors, withthermal sensors for feedback control), and measures, detects, samplesand/or senses the amount of power required to maintain the temperature.The required power may be proportional to the mass flow rate of materialover the sensor.

Radiation Sensors

[0165] Pyroelectric Sensors

[0166] With reference to FIG. 16, in one embodiment of the presentinvention, EIW 10 may include one or more pyroelectric sensors 74 tosense, detect, measure and/or monitor incident thermal energy associatedwith electromagnetic radiation on the wafer in, for example, a processchamber. Briefly, by way of background, pyroelectric sensor(s) operateon the pyroelectric effect in polarized crystals (for example, zincoxide). These crystals have a built-in electrical polarization levelwhich changes in accordance with an amount of incident thermal energy.

[0167] Pyroelectric sensors 74 are generally high impedance devices. Assuch, pyroelectric sensors 74 are often buffered using field effecttransistors. The pyroelectric sensors 74 may automatically zero to theambient temperature. As such, under this circumstance, sensors 74 mayrespond to rapid fluctuations.

[0168] The EIW 10 having a pyroelectric sensor 74 may monitor incidentthermal energy onto the wafer in, for example, a process chamber. An EIWaccording to this embodiment may be employed in, for example, baking(annealing) chambers and rapid-thermal-process (RTP) chambers.

[0169] It should be noted that crystals employed in pyroelectric sensors74 often exhibit piezoelectric effects as well as pyroelectric effects.Accordingly, it may be advantageous to implement the crystals of sensor74 on or in substrate 14 of EIW 10 in a manner that avoids strain on thecrystals.

[0170] It should be further noted that the earlier discussions of, forexample, electrical power supply techniques and circuitry, as well asthe communications link, techniques and circuitry, are fully applicableto this aspect of the present invention. For the sake of brevity, thosediscussions will not be repeated.

[0171] Detailed description of the physics and implementations ofpyroelectric sensors may be found in, for example, Microsensors, MEMSand Smart Devices, Gardner, et al., John Wiley & Sons, Incorporated,2001, the entire contents of which are incorporated herein by referenceherein.

[0172] Photoconductive and Photovoltaic Sensors

[0173] With reference to FIG. 17, in one embodiment of the presentinvention, EIW 10 may include one or more photoconductive and/orphotovoltaic sensors 76 to sense, sample, detect, measure and/or monitorradiation on the wafer. Briefly, photoconductive and photovoltaicsensors utilize the photoconductive and/or photovoltaic effects.Photoconductive materials become electrically conductive when exposed toradiation. Photovoltaic materials exhibit electrical voltage whenexposed to radiation. Both types of devices may be manufactured in asolid-state form, and specifically MEMS format. A detailed discussion ofthe physics and implementations may be found in, for example,Microsensors, MEMS and Smart Devices, by J. W. Gardner et al., JohnWiley & Sons, 2001, which, as mentioned above, is incorporated byreference herein.

[0174] It should be further noted that the earlier discussions of, forexample, electrical power supply techniques and circuitry, as well asthe communications link, techniques and circuitry, are fully applicableto these embodiments of the present invention. For the sake of brevity,those discussions will not be repeated.

[0175] Microantenna

[0176] In another embodiment of the present invention, EIW 10 mayinclude one or more microantennas to sense, sample, detect, measureand/or monitor radiation on or at the surface of the wafer. Radiationantennas may be made in the solid-state and/or MEMS format to collectradiation energy and output an electrical signal. A detailed discussionof the physics and implementations may be found in, for example,Microsensors, MEMS and Smart Devices, by J. W. Gardner et al., 2001(which, as mentioned above, is incorporated by reference herein in itsentirety.

Mechanical Sensors

[0177] The EIW of the present invention may include one or moremechanical sensors to sense, sample, detect, measure and/or monitor manyparameters including, but not limited to, acceleration, deceleration,displacement, flow rate of gas or liquid, force, torque, position,angle, pressure, and/or stress. These sensors may be based on MEMStechnology. These parameters may be significant to processes ofintegrated circuit manufacturing—for example, in CMP, the force and theresultant pressure applied to the wafer surface, when polishing, is asignificant parameter when determining the polishing rate. Theuniformity of polishing rates across the wafer may determine theuniformity of the resultant thin film, which in turn has far-reachingeffects on integrated circuit device performance and yield. In additionto the examples of the mechanical sensors described herein, thosesensors described and illustrated in Microsensors, MEMS and SmartDevices, by Gardner et al., (which, as mentioned above, is incorporatedherein by reference) may also be employed.

Pressure Sensors

[0178] With reference to FIG. 18, in one embodiment of the presentinvention, EIW 10 may include one or more pressure sensors 78 to sense,sample, detect, measure and/or monitor certain processes, for example, adeposition process. Microengineered pressure sensors may be based onthin membranes. In this regard, on one side of the membrane is anevacuated cavity (for absolute pressure measurement), and the other sideof the membrane is exposed to the pressure to be measured. Thedeformation of the membrane may be sensed, sampled, detected and/ormonitored using, for example, piezoresistors or capacitive techniques.

[0179] Piezoresistors and Piezoelectric Sensors

[0180] The EIW 10, in one embodiment of the present invention, mayinclude piezoresistors and/or piezoelectric pressure sensors to sense,detect, measure and/or sample stress, or stress related parameters oreffects, caused, induced or experienced during certain processes, forexample, during CMP processes or dry processes where the pressure of thegas is a controlled parameter of the process.

[0181] Briefly, by way of background, a change in resistance of amaterial with applied strain may be characterized as a piezoresistiveeffect. Piezoresistors may be fabricated in silicon; being just a smallvolume of silicon doped with impurities to make it an n-type or p-typedevice.

[0182] In operation, in response to a force applied to a piezoelectricmaterial, a charge is induced on the surface of the material. Theinduced charge is proportional to the applied force. The force appliedto the piezoelectric material may be determined by measuring, sampling,detecting or sensing the electrical potential across the crystal.Piezoelectric crystals may include zinc oxide and PZT (PbZrTiO3—leadzirconate titanate), which may be deposited and patterned onmicrostructures.

[0183] In one embodiment, piezoresistors are integrated into or ontosubstrate 14 of EIW 10 may be employed as a pressure sensor in order tosense, detect, sample and/or measure stress on or in the wafer caused bythe particular process. Stress related information may be useful incharacterizing the CMP process, since CMP relies on the pressure torealize the polishing effect. The EIW 10 of this embodiment of thepresent invention may also be useful in characterizing other processsteps that rely on or impact the pressure on the wafer, for example,those dry processing steps where the gas pressure is critical and/ortightly controlled aspect of the process.

[0184] It should be further noted that the earlier discussions of, forexample, electrical power supply techniques and circuitry, as well asthe communications link, techniques and circuitry, are fully applicableto these embodiments of the present invention. For the sake of brevity,those discussions will not be repeated.

[0185] Capacitive Sensors

[0186] With reference to FIG. 19, in one embodiment, EIW 10 may includeone or more capacitor sensor 80 to sense, detect, measure and/or samplesmall displacements (microns—tens of microns) with relatively highaccuracy (sub-nanometer) that may be caused, induced and/or experiencedduring processing. Briefly, by way of background, for two parallelconducting plates, separated by an insulating material, the capacitancebetween the plates may be expressed as:

C=εA/d

[0187] where

[0188] A=the area of the plates,

[0189] d=the distance between the plates, and

[0190] ε=the dielectric constant of the material between the plates.

[0191] It should be noted that the expression above assumes thecircumference of the plates is much larger than the distance betweenthem, so affects at the edges of the plates may be neglected.

[0192] From the above relationship, it may be readily seen that themeasured capacitance is inversely proportional to the distance betweenthe two plates. Thus, by incorporating capacitor sensors 80 (andassociated capacitance measuring circuitry 82) into or onto substrate 14of EIW 10, EIW 10 may sense, detect, measure, sample and/or monitordisplacements induced in semiconductor processing steps or stages. Itshould be noted that techniques to accurately measure capacitance arewell known arts to those skilled in the art of electronics.

[0193] It should be further noted that the electrical power supplytechniques and circuitry, as well as the communications link, techniquesand circuitry, discussed above are fully applicable to this embodimentof the present invention. For the sake of brevity, those discussionswill not be repeated.

Chemical Sensors

[0194] As mentioned above, EIW 10 of the present invention may includeone or more chemical sensors 44 to sense, sample, detect, measure and/ormonitor many different types of parameters relating to a change in thephysical and/or chemical properties of a given layer or structure due toa physical and/or chemical reaction, as well as the chemical environmentthat a product wafer is otherwise exposed to (see, for example, FIGS.5A, 5C, 5D and 5E). The chemical sensors 44 typically consist of achemically sensitive layer, whose physical properties change whenexposed to certain chemicals via physical or chemical reactions. Thesephysical changes may be sensed or sampled by a sensing transducer. Itshould be noted that many types of chemical sensors may be implementedon or in the EIW of the present invention. As such, all chemical sensorsthat may be integrated on or in an EIW, whether now known or laterdeveloped, are intended to fall within the scope of the presentinvention. For example, the chemical sensors described and illustratedin, for example, Chemical Sensing with Solid-State Devices, Madou etal., Academic Press, 1989, may be implemented. The entire contents ofChemical Sensing with Solid-State Devices, Madou et al., Academic Press,1989, are incorporated herein by reference herein..

[0195] Ion Sensitive Field Effect Transistor Sensors (ISFETs)

[0196] In one embodiment of the present invention, chemical sensor 44may be an ion sensitive field effect transistor. In this regard, withreference to FIG. 20, EIW 10 may include one or more ion sensitive fieldeffect transistors 84 to sense, sample, detect, measure and/or monitorthe concentration (activity level) of a particular ion in a solution. AnISFET is generally based on, or is similar or analogous in principal to,the enhancement mode metal-oxide-semiconductor field effect transistor(MOSFET) structure illustrated in FIG. 21.

[0197] Briefly, by way of background and with reference to FIG. 21, aMOSFET includes a gate electrode, insulated from the semiconductor(silicon) wafer by a thin layer of silicon dioxide (oxide). The bulk ofthe semiconductor (i.e. the substrate) is doped with impurities to makeit p-type silicon; in this material current is carried by positivecharge carriers called holes (since they are, in fact, the absence ofnegatively charged electrons). On either side of the gate are smallareas of silicon doped with impurities so that negatively chargedelectrons are the main carriers in these n-type silicon regions: thesource and the drain; n-type and p-type silicon are used to form diodes;current will flow from p-type to n-type, but typically not the other wayround. The bulk of the silicon substrate is connected to the mostnegative part of the circuit to prevent or limit the substrate'sinterference with the operation of the transistor (gate, drain, source).

[0198] In operation, a positive voltage is applied to the gate of theMOSFET. In response, holes from the region near the gate are repelledand electrons are attracted. This forms a narrow channel between thedrain and source where the majority charge carriers are electrons.Current may then flow through this channel, the amount of current thatflows depends on how large the channel is, and thus the voltage appliedto the gate.

[0199] With reference to FIG. 22, ISFET 84 includes an ion selectivemembrane, a source and a drain. The gate of a MOSFET represents or isanalogous to the ion selective membrane of the ISFET. The ISFET isimmersed in a solution. Ions in the solution interact with the ionselective membrane. That is, when there is a high concentration ofpositive ions in the solution, a predetermined concentration of thepositive ions will accumulate on or near the ion selective membrane,thereby forming a wide channel between the source and drain. With a lowconcentration of positive charged ions at or near the ion selectivemembrane, the channel will narrow due to the lower ion concentration.

[0200] In one embodiment, in order to ensure that the ISFET channel isbiased to an optimum or sufficient size about which sensing may takeplace, the solution is maintained at a reference potential by areference electrode. Generally, the reference potential is adjusted tomaintain a constant current flowing from drain to source, so the ionicconcentration will be directly related to the solution referencepotential with respect to the substrate potential.

[0201] Notably, the ISFET 84 may be incorporated into or onto substrate14 of EIW 10 to allow monitoring, sensing, sampling and/or detecting theion concentration in a liquid solution, for example, wet-etching, resistdevelopment, and CMP processing.

[0202] MEMS Sensors/Structures and Techniques

[0203] MEMS sensors/structures may be employed to construct differenttype of sensors. It should be noted that many types of MEMSsensors/structures may be implemented on or in the EIW of the presentinvention. As such, all MEMS sensors/structures that may be integratedon or in an EIW, whether now known or later developed, are intended tofall within the scope of the present invention. For example, the MEMSsensors/structures described in Microsensors, MEMS and Smart Devices,Gardner et al., 2001 (which, as mentioned above, is incorporated byreference) may be implemented in the present invention.

[0204] Resonant Sensors

[0205] With reference to FIG. 23, in one embodiment of the presentinvention, EIW 10 may include one or more resonant sensors 86 to sense,sample, detect, measure and/or monitor the processing conditions in, forexample, deposition processes. Briefly, by way of background, resonantsensors may be based on micromachined beams or bridges, which are drivento oscillate at their resonant frequency. Changes in the resonantfrequency of the device may be monitored, detected and/or measuredusing, for example, implanted piezoresistors. Such changes may also bemonitored, detected or measured using optical techniques as well.

[0206] With reference to FIG. 24A, the resonant frequency of the bridge,which is driven to resonance on a thin membrane, is related to, forexample, the force applied to it (between anchor points), its length,thickness, width, its mass, and the modulus of elasticity of thematerial from which it has been fabricated. In those instances where themembrane is deformed (see, for example, FIG. 24B), there is greaterpressure on one side of the bridge than the other. As such, the forceapplied to the bridge changes and, as a result, the resonant frequencyof the bridge changes. Therefore, resonant sensors may be employed tomonitor deposition processes, wherein the deposited material on thebridge will change the bridge's mass, and hence change its resonancefrequency, thereby allowing monitoring of, for example, the thickness ofthe deposited material.

[0207] Surface Acoustic Wave (SAW) Based Sensors and Actuators

[0208] With reference to FIG. 25, in one embodiment of the presentinvention, EIW 10 may include one or more SAW sensors 88 to sense,sample, detect, measure and/or monitor the temperature, radiation and/orviscosity of materials and/or substrate 14 during a given process.Briefly, a surface acoustic wave is typically generated by radiofrequency electrical signals via piezoelectric effects. There are manydifferent sensors designed and built to sense different parametersdetectable by SAW sensors 88. SAW sensors may be implemented using MEMStechniques and readily integrated into or onto EIW 10. SAW sensors 88may be designed to sense parameters including, but not limited to,temperature, radiation and/or viscosity. A detailed discussion of SAWsensors may be found in, for example, Microsensors, MEMS and SmartDevices, Gardner et al., 2001, which, as mentioned above, isincorporated by reference.

[0209] It should be further noted that the electrical power supplytechniques and circuitry, as well as the communications link, techniquesand circuitry, discussed above are fully applicable to this embodimentof the present invention. For the sake of brevity, those discussionswill not be repeated.

[0210] There are many inventions described and illustrated herein. Whilecertain embodiments, features, attributes and advantages of theinventions have been described and illustrated, it should be understoodthat many others, as well as different and/or similar embodiments,features, attributes and advantages of the present inventions, areapparent from the description and illustrations. As such, theembodiments, features, attributes and advantages of the inventionsdescribed and illustrated herein are not exhaustive and it should beunderstood that such other, similar, as well as different, embodiments,features, attributes and advantages of the present inventions are withinthe scope of the present invention.

[0211] Moreover, it should be noted that while the present invention(s)is described generally in the context of integrated circuit fabrication,the present invention(s) may be implemented in processes to manufactureother devices, components and/or systems including, for example, harddisk drives, magnetic thin-film heads for hard disk drives, flat paneldisplays, printed circuit board. Indeed, the present invention(s) may beemployed in the fabrication of any devices, components and/or systems,whether now known or later developed, that may benefit from the presentinvention(s).

[0212] In addition, an EIW according to the present invention mayinclude one, some or all of the sensors and/or sources described herein.Moreover, an EIW according to the present invention may include one ormore of the same or different sensors and/or sources (and associatedelectronics). Indeed, implementing one type of sensor may provideinformation that permits or facilitates detection, sampling, measuring,and/or monitoring of more than one parameter (for example, temperature,pressure and/or fluid flow rate). Thus, all combinations and/orpermutations of sensors and/or sources are intended to be within thescope of the inventions.

[0213] An EIW according to the present invention may include sensorsand/or sources that are integrated into or onto the substrate, ordisposed thereon (in the form of discrete devices), or combinationsthereof. For example, an EIW, according to one embodiment of the presentinvention, may include an integrated pressure sensor(s) and discreteoptical sensor(s).

[0214] Further, an EIW according to the present invention may beconfigured to simultaneously or serially sense, sample, detect, measure,and/or monitor information on the processing environment and/orprocessing progress during fabrication. For example, an EIW, accordingto one embodiment of the present invention, may (simultaneously orserially) detect, sample, measure, and/or monitor temperature andpressure using the same sensor or a plurality of the same or differentsensors (one or more of the same or different sensors dedicated totemperature and one or more of the same or different sensors dedicatedto pressure). In this way, such an EIW, addresses temperature andpressure operating parameters, which may be two critical processingconditions for certain processing steps.

[0215] Moreover, an EIW according to the present invention may beprogrammed to provide the sensed, sampled and/or detected data which isrepresentative of, for example, the processing environment during theactual process, thereafter, or a combination thereof. For example, anEIW according to one embodiment of the present invention may detect,sample, measure, and/or monitor temperature and pressure of a givenprocess using (1) a temperature sensor (or plurality of temperaturesensors) that store data in the resident storage devices for latertransmission and (2) a pressure sensor (or plurality of pressuresensors) that transmit data to an external device in real-time or nearreal-time. In this way, such an EIW, may provide certain criticalinformation regarding a first operating parameter (for example,pressure) immediately (i.e., in real-time) while a second operatingparameter (for example, temperature) is provided thereafter. Indeed,critical information regarding multiple parameters may be provided inreal-time (or near real-time) while other parameters are provided aftercompletion of the process under investigation.

[0216] Notably, the embodiments of the system, device, and componentsthereof (for example, the electrical source and communications layout,circuitry and techniques), as well as the methods, applications and/ortechniques, that are described and illustrated in the '806 Application,are incorporated by reference herein. For the sake of brevity, thosedescriptions and illustrations are not repeated herein.

[0217] Finally, it should be noted that the term “circuitry” or“electronics” may mean a circuit (whether integrated or otherwise), agroup of such circuits, a processor(s), a processor(s) implementingsoftware, or a combination of a circuit (whether integrated orotherwise), a group of such circuits, a processor(s) and/or aprocessor(s) implementing software. The term “circuit” may mean either asingle component or a multiplicity of components, either active and/orpassive, which are coupled together to provide or perform a desiredfunction. The term “data” may mean a current or voltage signal(s)whether in an analog or a digital form. The phrases “to sample” or“sample(s)” or the like, may mean, among other things, to record, tomeasure, to detect, to monitor, and/or to sense.

What is claimed is:
 1. A sensor unit for sensing process parameters of aprocess to manufacture an integrated circuit using integrated circuitprocessing equipment, the sensor unit comprising: a substrate having awafer-shaped profile; a first sensor, disposed on or in the substrate,to sample a first process parameter; and a second sensor, disposed on orin the substrate, to sample a second process parameter wherein thesecond process parameter is different from the first process parameter.2. The sensor unit of claim 1 further including at least one battery,disposed in the wafer-shaped substrate, to provide electrical power tothe first sensor.
 3. The sensor unit of claim 1 further includingcommunications circuitry disposed on the substrate, wherein thecommunications circuitry is coupled to the first and second sensors toprovide data to an external device wherein the data is representative ofthe first and second process parameters.
 4. The sensor unit of claim 1further including a first source, disposed on or in the substrate,wherein first source generates an interrogation signal and wherein thefirst sensor uses the interrogation signal from the first source tosample the first process parameter.
 5. The sensor unit of claim 4further including a second source, disposed on or in the substrate,wherein second source generates an interrogation signal and wherein thesecond sensor uses the interrogation signal from the second source tosample the second process parameter.
 6. The sensor unit of claim 4wherein the first sensor and first source operate in an end-point mode.7. The sensor unit of claim 6 wherein the second sensor operates in areal-time mode.
 8. The sensor unit of claim 7 further including datastorage to store data which is representative of the second parameter.9. The sensor unit of claim 7 wherein the sensor unit further includes:data compression circuitry to compress the data which is representativeof the second parameter; communication circuitry, coupled to the datacompression circuitry, to provide the data which is representative ofthe second parameter to external circuitry; and at least onerechargeable battery, to provide electrical power to the datacompression circuitry and the communication circuitry.
 10. The sensorunit of claim 1 wherein the first sensor operates in a real-time mode.11. The sensor unit of claim 10 further including: data storage to storedata which is representative of the first parameter; data compressioncircuitry to compress the data which is representative of the firstparameter; communication circuitry, coupled to the data compressioncircuitry, to provide the data which is representative of the firstparameter to external circuitry; and at least one rechargeable battery,to provide electrical power to the data compression circuitry and thecommunication circuitry.
 12. The sensor unit of claim 10 wherein thefirst sensor samples the first parameter periodically or continuouslywhile the sensor unit is disposed in the integrated circuit processingequipment and undergoing processing.
 13. The sensor unit of claim 1wherein the first sensor is a temperature sensor and the second sensoris a pressure sensor.
 14. The sensor unit of claim 1 wherein the firstsensor is a temperature sensor and the second sensor is a chemicalsensor.
 15. The sensor unit of claim 1 wherein the first sensor is atemperature sensor and the second sensor is a surface tension sensor.16. The sensor unit of claim 1 wherein the first sensor is a temperaturesensor and the second sensor is a surface stress sensor.
 17. A sensorunit for sensing a first process parameter of a process to manufacturean integrated circuit using integrated circuit processing equipment, thesensor unit comprising: a substrate having a wafer-shaped profile; asource, disposed on or in the substrate, to generate an interrogationsignal; and a first sensor, disposed on or in the substrate, to sample afirst process parameter using the interrogation signal from the source.18. The sensor unit of claim 17 wherein the source and the first sensoroperate in an end-point mode.
 19. The sensor unit of claim 17 whereinthe source and the first sensor operate in a real-time mode.
 20. Thesensor unit of claim 19 further including data storage to store datawhich is representative of the first parameter.
 21. The sensor unit ofclaim 19 wherein the sensor unit further includes: data compressioncircuitry to compress the data which is representative of the firstparameter; communication circuitry, coupled to the data compressioncircuitry, to provide the data which is representative of the firstparameter to external circuitry; and at least one rechargeable battery,to provide electrical power to the data compression circuitry and thecommunication circuitry.
 22. The sensor unit of claim 17 wherein thesource is a VCSEL or LED.
 23. The sensor unit of claim 22 wherein thefirst sensor is a CMOS devices, charge coupled devices, or photodiode.24. The sensor unit of claim 23 wherein the first parameter is thesurface profile.
 25. The sensor unit of claim 23 wherein the sensor unitfurther includes a predetermined surface layer which is disposed abovethe source and the first sensor.
 26. The sensor unit of claim 25 whereinthe predetermined surface layer is comprised of a material thatfacilitates light propagation or scattering.
 27. The sensor unit ofclaim 17 wherein the first sensor periodically or continuously samplesthe first parameter while the sensor unit is disposed in the integratedcircuit processing equipment and undergoing processing.
 28. The sensorunit of claim 27 further including data storage, coupled to the firstsensor, to store data which is representative of the first parameter.29. The sensor unit of claim 27 wherein the sensor unit furtherincludes: communication circuitry, coupled to the data compressioncircuitry, to provide the data which is representative of the firstparameter to external circuitry; and at least one rechargeable battery,to provide electrical power to the data compression circuitry and thecommunication circuitry.
 30. The sensor unit of claim 29 wherein: thesource is a VCSEL or LED; the first sensor is a CMOS devices, chargecoupled devices, or photodiode; and wherein the sensor unit furtherincludes a predetermined surface layer which is disposed above thesource and the first sensor.
 31. The sensor unit of claim 30 wherein thefirst sensor samples the intensity of reflected or scattered light. 32.The sensor unit of claim 31 further including a temperature sensor tosample temperature, in a real-time mode, while the sensor unit isdisposed in the integrated circuit processing equipment and undergoingprocessing.
 33. The sensor unit of claim 32 wherein the temperaturesensor periodically or continuously samples the temperature.
 34. Asensor unit for sensing a first process parameter of a process tomanufacture an integrated circuit using integrated circuit processingequipment, the sensor unit comprising: a substrate having a wafer-shapedprofile; a first source, disposed on or in the substrate, to generate aninterrogation signal; and a first sensor array including a plurality offirst sensors disposed on or in the substrate, wherein the first sensorssample a first process parameter using the interrogation signal; asecond sensor array including a plurality of second sensors disposed onor in the substrate, wherein the second sensors sample a second processparameter wherein the second process parameter is different from thefirst process parameter.
 35. The sensor unit of claim 34 wherein thesecond sensors operate in a end-point mode.
 36. The sensor unit of claim34 wherein the second sensors operate in a real-time mode and sample thesecond process parameter continuously or periodically while the sensorunit is disposed in the integrated circuit processing equipment andundergoing processing.
 37. The sensor unit of claim 34 wherein the firstsource and the first sensors operate in an end-point mode.
 38. Thesensor unit of claim 34 wherein the first source and the first sensorsoperate in a real-time mode.
 39. The sensor unit of claim 38 furtherincluding: data storage to store data sampled by the first sensors;communication circuitry, coupled to the data storage, to provide thedata which is representative of the first parameter to externalcircuitry; and at least one rechargeable battery, to provide electricalpower to the first source, the first sensors, the data storage and thecommunication circuitry.
 40. The sensor unit of claim 38 wherein: thefirst source is a VCSEL or LED; the first sensor is a CMOS devices,charge coupled devices, or photodiode; and wherein the sensor unitfurther includes a predetermined surface layer which is disposed abovethe first source and the first sensor.
 41. The sensor unit of claim 40wherein the first sensor samples the intensity of reflected or scatteredlight.
 42. The sensor unit of claim 41 wherein the second sensors aretemperature sensors.
 43. The sensor unit of claim 42 wherein thetemperature sensors sample temperature, in a real-time mode, while thesensor unit is disposed in the integrated circuit processing equipmentand undergoing processing.
 44. The sensor unit of claim 43 wherein thetemperature sensors periodically or continuously sample the temperature.45. The sensor unit of claim 34 wherein the second sensors are pressuresensors.
 46. The sensor unit of claim 34 wherein the second sensors arelight intensity sensors.
 47. The sensor unit of claim 34 wherein thesecond sensors are chemical sensors.
 48. The sensor unit of claim 34wherein the second sensors are surface tension sensors.
 49. The sensorunit of claim 34 wherein the second sensors are surface stress sensors.50. The sensor unit of claim 34 wherein the second sensors are surfaceprofile sensors.